Thermal instability, safety hazard

Follow-up Tests. In our follow-up tests we want to better define at what temperature we can detect the thermal instability, and to gain some knowledge about how much of a hazard the instability represents. The majority of this work is done with an instrument called a Sikarex Safety Calorimeter (3,4) xt consists of a sample oven, a control and measurement module, and a recorder. In the sample oven is placed 10-30 g of sample in either an open glass tube, a closed glass tube with a capillary bleed, or a stainless steel autoclave. The control and measurement module controls the oven temperature and measures the sample and oven jacket temperatures. 

Schulz, N., Pilz, V. and Schacke, H.. 1983. Controlling thermal instabilities in chemical process. Loss Prevention and Safety Promotion in the Process litdustries. Volume 3 — Chemical Process Hazards. Symposium Series No. 82. B1 (IChemE, Rugby, UK). 

No process can be made one hundrend percent safe. However, one can identify hazards and, if the hazard is severe, avoid such a chemical or process, or if the hazard is moderate, take precautions that minimize the risk. Safety hazards can be divided into four categories thermal instability, toxicity, flammability, and explosiveness. Typically the in-house safety laboratory measures the decomposition temperature of all reagents, intermediates, solvents, distillation residues and evaporation residues, and any exotherms associated with the decomposition, so that one stays well below these temperatures in the process. The heat of reactions is measured to ensure adequate cooling capacity of the reactor before scaling up a reaction. This minimizes the risk of runaway reactions. 

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